Settable Compositions Comprising Interground Perlite and Hydraulic Cement

ABSTRACT

Methods and compositions are disclosed that comprise interground perlite and hydraulic cement. An embodiment provides a method of cementing comprising: providing a settable composition comprising perlite, hydraulic cement, and water, wherein the perlite and hydraulic cement are interground prior to combination with the water to form the settable composition; and allowing the settable composition to set.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S. patentapplication Ser. No. 12/975,196, entitled “Settable CompositionsComprising Unexpanded Perlite and Methods of Cementing in SubterraneanFormations,” filed on Dec. 21, 2010, the entire disclosure of which isincorporated herein by reference.

BACKGROUND

The present invention relates to cementing operations and, moreparticularly, in certain embodiments, to methods and compositions thatcomprise interground perlite and hydraulic cement.

In general, well treatments include a wide variety of methods that maybe performed in oil, gas, geothermal and/or water wells, such asdrilling, completion and workover methods. The drilling, completion andworkover methods may include, but are not limited to, drilling,fracturing, acidizing, logging, cementing, gravel packing, perforatingand conformance methods. Many of these well treatments are designed toenhance and/or facilitate the recovery of desirable fluids from asubterranean well.

In cementing methods, such as well construction and remedial cementing,settable compositions are commonly utilized. As used herein, the term“settable composition” refers to a composition(s) that hydraulicallysets or otherwise develops compressive strength. Settable compositionsmay be used in primary cementing operations whereby pipe strings, suchas casing and liners, are cemented in well bores. In performing primarycementing, a settable composition may be pumped into an annulus betweena subterranean formation and the pipe string disposed in thesubterranean formation. The settable composition should set in theannulus, thereby forming an annular sheath of hardened cement (e.g., acement sheath) that should support and position the pipe string in thewell bore and bond the exterior surface of the pipe string to the wallsof the well bore. Settable compositions also may be used in remedialcementing methods, such as the placement of cement plugs, and in squeezecementing for sealing voids in a pipe string, cement sheath, gravelpack, formation, and the like.

The hydration of the cement in these cementing methods is a complexprocess because several phases may take part in the reactionsimultaneously. In order to control the reaction processes to render thecompositions suitable for well cementing, various additives such asretarders, strength enhancers, and accelerators may be added. However,the operating conditions for wells are becoming more challenging anddemanding, and the search for new materials continues to meet thesechallenges. For instance, cement slurries used in well cementing oftenencounter problems of gaining sufficient strength in a reasonable amountof time for well operations to continue. The costs associated withwait-on-cement (“WOC”) play an important role in well cementing.

SUMMARY

The present invention relates to cementing operations and, moreparticularly, in certain embodiments, to methods and compositions thatcomprise interground perlite and hydraulic cement.

An embodiment provides a method of cementing comprising: providing asettable composition comprising perlite, hydraulic cement, and water,wherein the perlite and hydraulic cement are interground prior tocombination with the water to form the settable composition; andallowing the settable composition to set.

Another embodiment provides a method of cementing comprising: providinga settable composition comprising unexpanded perlite, hydraulic cement,and water, wherein the unexpanded perlite and hydraulic cement areinterground prior to combination with the water to form the settablecomposition; introducing the settable composition into a well bore; andallowing the settable composition to set.

Yet another embodiment provides a composition comprising intergroundperlite and hydraulic cement.

The features and advantages of the present invention will be readilyapparent to those skilled in the art. While numerous changes may be madeby those skilled in the art, such changes are within the spirit of theinvention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments of the settable compositions of the present invention maycomprise perlite. Perlite suitable for use in embodiments of the presentinvention includes expanded perlite and unexpanded perlite. In someembodiments, the settable composition may comprise perlite intergroundwith a hydraulic cement. In some embodiments, the settable compositionsmay comprise unexpanded perlite with cement kiln dust (“CKD”), pumicite,or a combination thereof. There may be several potential advantages tothe methods and compositions of the present invention, only some ofwhich may be alluded to herein. One of the many potential advantages ofembodiments of the present invention is that the inclusion of theunexpanded perlite in embodiments of the settable composition mayincrease the compressive strength of the settable composition aftersetting. Another potential advantage of embodiments of the presentinvention is that the CKD, unexpanded perlite, pumicite, or acombination thereof may be used to reduce the amount of a higher costcomponent, such as Portland cement, resulting in a more economicalsettable composition. Yet another potential advantage of embodiments ofthe present invention is that reduction of the amount of Portland cementcan reduce the carbon footprint of the cementing operation.

Perlite is an ore and generally refers to a naturally occurringvolcanic, amorphous siliceous rock comprising mostly silicon dioxide andaluminum oxide. A characteristic of perlite is that it may expand toform a cellular, high-porosity particle or hollow sphere containingmulti-cellular cores when exposed to high temperatures due to the suddenvaporization of water within the perlite. The expanded perlite may beused as a density-reducing additive for making lightweight settablecompositions. Perlite suitable for use in embodiments of the presentinvention includes expanded perlite and unexpanded perlite. In someembodiments, the perlite may comprise unexpanded perlite.

It has recently been discovered the addition of unexpanded perlite tosettable compositions comprising CKD and/or pumicite may provideunexpected increases in compressive strengths. In accordance withembodiments of the present invention, the unexpanded perlite may be usedto increase the compressive strength of settable compositions comprisingCKD and/or pumicite. In addition, unexpanded perlite can increase thecompressive strength of settable compositions comprising Portlandcement. It is believed that the unexpanded perlite may be particularlysuited for use at elevated well bore temperatures in accordance withembodiments of the present invention, such as at temperatures greaterthan about 80° F., alternatively greater than about 120° F., andalternatively greater than about 140° F.

In one embodiment, unexpanded perlite may be used, among other things,to replace higher cost cementitious components, such as Portland cement,resulting in more economical settable compositions. In addition,substitution of the Portland cement for the unexpanded perlite shouldresult in a settable composition with a reduced carbon footprint.

In present embodiments, the perlite can be ground to any size suitablefor use in cementing operations. In an embodiment, the perlite is groundto a mean particle size of about 1 micron to about 400 microns,alternatively, about 1 micron to about 100 microns and, alternatively,about 1 micron to about 25 microns. The mean particle size correspondsto d50 values as measured by commercially available particle sizeanalyzers such as those manufactured by Malvern Instruments,Worcestershire, United Kingdom. In another embodiment, the perlite has aparticle size distribution of about 1 micron to about 1,000 microns witha mean particle size of about 1 micron to about 100 microns. Theparticle size distribution corresponds to the maximum and minimum sizesallowed in the distribution. An example of a suitable ground perlitethat is unexpanded is available from Hess Pumice Products, Inc., MaladCity, Id., under the tradename IM-325 with a mesh size of 325.

The perlite may be included in the settable compositions in an amountsufficient to provide the desired compressive strength, density, costreduction, and/or reduced carbon footprint. In some embodiments, theperlite may be present in the settable compositions of the presentinvention in an amount in the range of from about 1% to about 75% byweight of cementitious components. Cementitious components include thosecomponents or combinations of components of the settable compositionsthat hydraulically set, or otherwise harden, to develop compressivestrength, including, for example, perlite, CKD, fly ash, pumicite, slag,lime, shale, and the like. For example, the perlite may be present in anamount ranging between any of and/or including any of about 5%, about10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%,about 45%, about 50%, about 55%, about 60%, about 65%, or about 70%. Inspecific embodiments, the perlite may be present in the settablecompositions in an amount in the range of from about 5% to about 50% byweight of cementitious components. In another embodiment, the perlitemay be present in an amount in the range of from about 10% to about 40%by weight of cementitious components. In yet another embodiment, theperlite may be present in an amount in the range of from about 20% toabout 30% by weight of cementitious components. One of ordinary skill inthe art, with the benefit of this disclosure, will recognize theappropriate amount of perlite to include for a chosen application.

In one particular embodiment, the perlite can be interground withhydraulic cement. In one embodiment, the hydraulic cement may be aPortland cement, such as those classified as ASTM Type V cement. Inanother embodiment, the perlite can be interground with hydraulic cementand pumicite. In another embodiment, the perlite can be interground withhydraulic cement and CKD. The term “interground” or “intergrinding” asused herein means using a grinder (e.g., ball mill, rod mill, etc.) toreduce the particle size of the specified components. It is believedthat intergrinding the perlite and hydraulic cement may improve theproperties of the subsequent settable composition. For example, it isbelieved that intergrinding the perlite and hydraulic cement may provideaccelerated strength development, in the subsequent settablecompositions, as compared to intergrinding pumicite and hydrauliccement. By way of further example, it is believed that intergrinding theperlite and hydraulic cement may provide increased strength propertiesof the subsequent settable compositions, as compared to blendingseparately ground material.

In some embodiments, the interground perlite and hydraulic cement maycomprise perlite in an amount of about 0.1% to about 99% by weight ofthe interground perlite and hydraulic cement and hydraulic cement in anamount of about 0.1% to about 99% by weight of the interground perliteand hydraulic cement. For example, the perlite may be present in anamount ranging between any of and/or including any of about 5%, about10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%,about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about75%, about 80%, about 85%, about 90%, or about 95% by weight of theinterground perlite and hydraulic cement. By way of further example, thehydraulic cement may be present in an amount ranging between any ofand/or including any of about 5%, about 10%, about 15%, about 20%, about25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%,about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about90%, or about 95% by weight of the interground perlite and hydrauliccement.

In accordance with embodiments, the hydraulic cement and perlite may becombined and ground to any size suitable for use in cementingoperations. In another embodiment, the hydraulic cement and/or perlitemay be ground prior to combination. In yet another embodiment, theperlite may be ground to a first particle size and then interground withthe hydraulic cement to a second particle size. In an embodiment, theinterground perlite and hydraulic cement has a mean particle size ofabout 0.1 microns to about 400 microns, including an amount rangingbetween any of and/or including any of about 0.5 microns, about 1micron, about 2 microns, about 5 microns, about 10 microns, about 25microns, about 50 microns, about 75 microns, about 100 microns, about150 microns, about 200 microns, about 250 microns, about 300 microns, orabout 350 microns. For example, the interground perlite and hydrauliccement may have a mean particle size of about 0.5 microns to about 50microns. By way of further example, the interground perlite andhydraulic cement may have a mean particle size of about 0.5 microns toabout 10 microns. The mean particle size corresponds to d50 values asmeasured by commercially available particle size analyzers such as thosemanufactured by Malvern Instruments, Worcestershire, United Kingdom. Insome embodiments, the interground perlite and hydraulic cement may havea bimodal particle size distribution. For example, the intergroundperlite and hydraulic cement may have a bimodal particle sizedistribution with a first peak from about 1 microns to about 7 micronsand a second peak from about 7 microns to about 15 microns,alternatively, a first peak from about 3 microns to about 5 microns anda second peak from about 9 microns to about 11 microns, andalternatively, a first peak of about 4 microns and a second peak ofabout 10 microns.

In some embodiments, the interground perlite and hydraulic cement may bepresent in an amount in the range of from about 0.1% to about 100% byweight of cementitious components in the settable composition. Forexample, the interground perlite and hydraulic cement may be present inan amount ranging between any of and/or including any of about 5%, about10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%,about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about75%, about 80%, about 85%, about 90%, or about 95% by weight ofcementitious components. One of ordinary skill in the art, with thebenefit of this disclosure, will recognize the appropriate amount of theinterground perlite and hydraulic cement to include for a chosenapplication.

Embodiments of the settable compositions further may comprise hydrauliccement. As previously mentioned, the hydraulic cement may be intergroundwith the perlite in accordance with certain embodiments. Any of avariety of hydraulic cements suitable for use in subterranean cementingoperations may be used in accordance with embodiments of the presentinvention. Suitable examples include hydraulic cements that comprisecalcium, aluminum, silicon, oxygen and/or sulfur, which set and hardenby reaction with water. Such hydraulic cements, include, but are notlimited to, Portland cements, pozzolana cements, gypsum cements,high-alumina-content cements, slag cements, silica/lime cements andcombinations thereof. In certain embodiments, the hydraulic cement maycomprise a Portland cement. The Portland cements that may be suited foruse in embodiments of the present invention are classified as Class A,C, H and G cements according to American Petroleum Institute,Recommended Practice for Testing Well Cements, API Specification 10B-2(ISO 10426-2), First edition, July 2005. In addition, in someembodiments, cements suitable for use in the present invention mayinclude cements classified as ASTM Type I, II, III, IV, or V.

The hydraulic cement may be included in the settable compositions in anamount sufficient for a particular application. In some embodiments, thehydraulic cement may be present in the settable compositions in anamount in the range of from about 0.1% to about 99% by weight ofcementitious components. For example, the hydraulic cement may bepresent in an amount ranging between any of and/or including any ofabout 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%,about 70%, about 75%, about 80%, about 85%, about 90%, or about 95% byweight of cementitious components. One of ordinary skill in the art,with the benefit of this disclosure, will recognize the appropriateamount of the hydraulic cement to include for a chosen application.

Embodiments of the settable compositions generally further may compriseCKD. It should be understood that embodiments of the present inventionalso may encompass intergrinding the CKD with the perlite and thehydraulic cement. Usually, large quantities of CKD are collected in theproduction of cement that are commonly disposed of as waste. Disposal ofthe waste CKD can add undesirable costs to the manufacture of thecement, as well as the environmental concerns associated with itsdisposal. The chemical analysis of CKD from various cement manufacturesvaries depending on a number of factors, including the particular kilnfeed, the efficiencies of the cement production operation, and theassociated dust collection systems. CKD generally may comprise a varietyof oxides, such as SiO₂, Al₂O₃, Fe₂O₃, CaO, MgO, SO₃, Na₂O, and K₂O.

The CKD generally may exhibit cementitious properties, in that it mayset and harden in the presence of water. In accordance with embodimentsof the present invention, the CKD may be used, among other things, toreplace higher cost cementitious components, such as Portland cement,resulting in more economical settable compositions. In addition,substitution of the Portland cement for the CKD can result in a settablecomposition with a reduced carbon footprint.

The CKD may be included in the settable compositions in an amountsufficient to provide the desired compressive strength, density, costreduction, and/or reduced carbon footprint. In some embodiments, the CKDmay be present in the settable compositions of the present invention inan amount in the range of from about 1% to about 95% by weight ofcementitious components. For example, the CKD may be present in anamount ranging between any of and/or including any of about 5%, about10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%,about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about75%, about 80%, or about 90%. In specific embodiments, the CKD may bepresent in the settable compositions in an amount in the range of fromabout 5% to about 95% by weight of cementitious components. In anotherembodiment, the CKD may be present in an amount in the range of fromabout 50% to about 90% by weight of cementitious components. In yetanother embodiment, the CKD may be present in an amount in the range offrom about 60% to about 80% by weight of cementitious components. One ofordinary skill in the art, with the benefit of this disclosure, willrecognize the appropriate amount of CKD to include for a chosenapplication.

Embodiments of the settable compositions further may comprise pumicite.It should be understood that embodiments of the present invention alsomay encompass intergrinding the pumicite with the perlite and thehydraulic cement. Generally, pumicite is a volcanic rock that exhibitscementitious properties, in that it may set and harden in the presenceof hydrated lime and water. Hydrated lime may be used in combinationwith the pumicite, for example, to provide sufficient calcium ions forthe pumicite to set. In accordance with embodiments of the presentinvention, the pumicite may be used, among other things, to replacehigher cost cementitious components, such as Portland cement, resultingin more economical settable compositions. As previously mentioned,replacement of the Portland cement should also result in a settablecomposition with a reduced carbon footprint.

Where present, the pumicite may be included in an amount sufficient toprovide the desired compressive strength, density, cost reduction and/orreduced carbon footprint for a particular application. In someembodiments, the pumicite may be present in the settable compositions ofthe present invention in an amount in the range of from about 1% toabout 95% by weight of cementitious components. For example, thepumicite may be present in an amount ranging between any of and/orincluding any of about 5%, about 10%, about 15%, about 20%, about 25%,about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about60%, about 65%, about 70%, about 75%, about 80%, or about 90% by weightof cementitious components. In specific embodiments, the pumicite may bepresent in the settable compositions of the present invention in anamount in the range of from about 5% to about 95% by weight ofcementitious components. In another embodiment, the pumicite may bepresent in an amount in the range of from about 5% to about 80% byweight of cementitious components. In yet another embodiment, thepumicite may be present in an amount in the range of from about 10% toabout 50% by weight of cementitious components. In yet anotherembodiment, the pumicite may be present in an amount in the range offrom about 25% to about 50% by weight of cementitious components. One ofordinary skill in the art, with the benefit of this disclosure, willrecognize the appropriate amount of the pumicite to include for a chosenapplication.

Embodiments of the settable compositions further may comprise lime. Incertain embodiments, the lime may be hydrated lime. The lime may beincluded in embodiments of the settable compositions, for example, toform a hydraulic composition with other components of the settablecompositions, such as the pumicite, fly ash, slag, and/or shale. Wherepresent, the lime may be included in the settable compositions in anamount sufficient for a particular application. In some embodiments, thelime may be present in an amount in the range of from about 1% to about40% by weight of cementitious components. For example, the lime may bepresent in an amount ranging between any of and/or including any ofabout 5%, about 10%, about 15%, about 20%, about 25%, about 30%, orabout 35%. In specific embodiments, the lime may be present in an amountin the range of from about 5% to about 20% by weight of cementitiouscomponents. One of ordinary skill in the art, with the benefit of thisdisclosure, will recognize the appropriate amount of the lime to includefor a chosen application.

In accordance with certain embodiments, a mixture of pumicite andhydraulic cement, such as Portland cement may be included in thesettable composition. In an embodiment, the cement/pumicite mixturecontains hydraulic cement in an amount of about 25% to about 75% byweight of the mixture and pumicite in an amount of about 25% to about75% by weight of the mixture. In an embodiment, the cement/pumicitemixture contains about 40% hydraulic cement by weight and about 60%pumicite by weight. In an embodiment, the cement/pumicite mixture maycomprise hydraulic cement interground with pumicite. In one embodiment,the hydraulic cement may comprise Portland cement classified as ASTMType V cement. In accordance with embodiments, the Portland cement andpumicite may be combined and ground to any size suitable for use incementing operations. In another embodiment, the Portland cement andpumicite may be ground prior to combination. In an embodiment, thecement/pumicite mixture of Portland cement and pumicite has a meanparticle size of about 0.1 microns to about 400 microns, alternatively,about 0.5 microns to about 50 microns, and alternatively, about 0.5microns to about 10 microns. The mean particle size corresponds to d50values as measured by commercially available particle size analyzerssuch as those manufactured by Malvern Instruments, Worcestershire,United Kingdom. An example of a suitable cement/pumicite mixture isavailable from Halliburton Energy Services, Inc., under the trade nameFineCem™ 925 cement.

It is believed that hydraulic cement interground with pumicite when usedin a settable composition in combination with unexpanded perlite mayprovide synergistic effects. For example, it is believed that thecombination of unexpanded perlite and the cement/pumicite mixture mayprovide significantly higher compressive strength, particularly atelevated well bore temperatures. Accordingly, the combination ofunexpanded perlite and the cement/pumicite mixture may be particularlysuited for use in settable compositions at elevated well boretemperatures, such as at temperatures greater than about 80° F.,alternatively greater than about 120° F., and alternatively greater thanabout 140° F.

Embodiments of the settable compositions further may comprise fly ash. Avariety of fly ashes may be suitable, including fly ash classified asClass C and Class F fly ash according to American Petroleum Institute,API Specification for Materials and Testing for Well Cements, APISpecification 10, Fifth Ed., Jul. 1, 1990. Class C fly ash comprisesboth silica and lime so that, when mixed with water, it should set toform a hardened mass. Class F fly ash generally does not containsufficient lime, so an additional source of calcium ions is typicallyrequired for the Class F fly ash to form a hydraulic composition. Insome embodiments, lime may be mixed with Class F fly ash in an amount inthe range of about 0.1% to about 25% by weight of the fly ash. In someinstances, the lime may be hydrated lime. Suitable examples of fly ashinclude, but are not limited to, POZMIX® A cement additive, commerciallyavailable from Halliburton Energy Services, Inc.

Where present, the fly ash generally may be included in the settablecompositions in an amount sufficient to provide the desired compressivestrength, density, and/or cost. In some embodiments, the fly ash may bepresent in the settable compositions of the present invention in anamount in the range of about 1% to about 75% by weight of cementitiouscomponents. For example, the fly ash may be present in an amount rangingbetween any of and/or including any of about 5%, about 10%, about 20%,about 30%, about 40%, about 50%, about 60%, or about 70% by weight ofcementitious components. In specific embodiments, the fly ash may bepresent in an amount in the range of about 10% to about 60% by weight ofcementitious components. One of ordinary skill in the art, with thebenefit of this disclosure, will recognize the appropriate amount of thefly ash to include for a chosen application.

Embodiments of the settable compositions further may comprise slagcement. In some embodiments, a slag cement that may be suitable for usemay comprise slag. Slag generally does not contain sufficient basicmaterial, so slag cement further may comprise a base to produce ahydraulic composition that may react with water to set to form ahardened mass. Examples of suitable sources of bases include, but arenot limited to, sodium hydroxide, sodium bicarbonate, sodium carbonate,lime, and combinations thereof.

Where present, the slag cement generally may be included in the settablecompositions in an amount sufficient to provide the desired compressivestrength, density, and/or cost. In some embodiments, the slag cement maybe present in the settable compositions of the present invention in anamount in the range of about 1% to about 75% by weight of cementitiouscomponents. For example, the slag cement may be present in an amountranging between any of and/or including any of about 5%, about 10%,about 20%, about 30%, about 40%, about 50%, about 60%, or about 70% byweight of cementitious components. In specific embodiments, the slagcement may be present in an amount in the range of about 5% to about 50%by weight of cementitious components. One of ordinary skill in the art,with the benefit of this disclosure, will recognize the appropriateamount of the slag cement to include for a chosen application.

Embodiments of the settable compositions further may comprisemetakaolin. Generally, metakaolin is a white pozzolan that may beprepared by heating kaolin clay, for example, to temperatures in therange of about 600° C. to about 800° C. In some embodiments, themetakaolin may be present in the settable compositions of the presentinvention in an amount in the range of about 1% to about 75% by weightof cementitious components. For example, the metakaolin may be presentin an amount ranging between any of and/or including any of about 5%,about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, orabout 70% by weight of cementitious components. In specific embodiments,the metakaolin may be present in an amount in the range of about 10% toabout 50% by weight of cementitious components. One of ordinary skill inthe art, with the benefit of this disclosure, will recognize theappropriate amount of the metakaolin to include for a chosenapplication.

Embodiments of the settable compositions further may comprise shale.Among other things, shale included in the settable compositions mayreact with excess lime to form a suitable cementing material, forexample, calcium silicate hydrate. A variety of shales may be suitable,including those comprising silicon, aluminum, calcium, and/or magnesium.An example of a suitable shale comprises vitrified shale. Suitableexamples of vitrified shale include, but are not limited to,PRESSUR-SEAL FINE LCM material and PRESSUR-SEAL COARSE LCM material,which are commercially available from TXI Energy Services, Inc.Generally, the shale may have any particle size distribution as desiredfor a particular application. In certain embodiments, the shale may havea particle size distribution in the range of about 37 micrometers toabout 4,750 micrometers.

Where present, the shale may be included in the settable compositions ofthe present invention in an amount sufficient to provide the desiredcompressive strength, density, and/or cost. In some embodiments, theshale may be present in the settable compositions of the presentinvention in an amount in the range of about 1% to about 75% by weightof cementitious components. For example, the shale may be present in anamount ranging between any of and/or including any of about 5%, about10%, about 20%, about 30%, about 40%, about 50%, about 60%, or about 70%by weight of cementitious components. In specific embodiments, the shalemay be present in an amount in the range of about 10% to about 35% byweight of cementitious components. One of ordinary skill in the art,with the benefit of this disclosure, will recognize the appropriateamount of the shale to include for a chosen application.

Embodiments of the settable compositions further may comprise zeolite.Zeolites generally are porous alumino-silicate minerals that may beeither a natural or synthetic material. Synthetic zeolites are based onthe same type of structural cell as natural zeolites, and may comprisealuminosilicate hydrates. As used herein, the term “zeolite” refers toall natural and synthetic forms of zeolite. Examples of suitablezeolites are described in more detail in U.S. Pat. No. 7,445,669. Anexample of a suitable source of zeolite is available from the C2CZeolite Corporation of Calgary, Canada. In some embodiments, the zeolitemay be present in the settable compositions of the present invention inan amount in the range of about 1% to about 65% by weight ofcementitious components. For example, the zeolite may be present in anamount ranging between any of and/or including any of about 5%, about10%, about 20%, about 30%, about 40%, about 50%, or about 60% by weightof cementitious components. In specific embodiments, the zeolite may bepresent in an amount in the range of about 10% to about 40% by weight ofcementitious components. One of ordinary skill in the art, with thebenefit of this disclosure, will recognize the appropriate amount of thezeolite to include for a chosen application.

Embodiments of the settable compositions further may comprise a setretarding additive. As used herein, the term “set retarding additive”refers to an additive that retards the setting of the settablecompositions of the present invention. Examples of suitable setretarding additives include, but are not limited to, ammonium, alkalimetals, alkaline earth metals, metal salts of sulfoalkylated lignins,organic acids (e.g., hydroxycarboxy acids), copolymers that compriseacrylic acid or maleic acid, and combinations thereof. One example of asuitable sulfoalkylated lignin comprises a sulfomethylated lignin.Suitable set retarding additives are disclosed in more detail in U.S.Pat. No. Re. 31,190, the entire disclosure of which is incorporatedherein by reference. Suitable set retarding additives are commerciallyavailable from Halliburton Energy Services, Inc. under the trademarksHR® 4, HR® 5, HR® 7, HR® 12, HR®15, HR®25, HR®601, SCR™ 100, and SCR™500 retarders. Generally, where used, the set retarding additive may beincluded in the settable compositions of the present invention in anamount sufficient to provide the desired set retardation. In someembodiments, the set retarding additive may be present in the settablecompositions of the present invention an amount in the range of about0.1% to about 5% by weight of cementitious components, including anamount ranging between any of and/or including any of about 0.5%, about1%, about 2%, about 3%, or about 4% by weight of cementitiouscomponents. One of ordinary skill in the art, with the benefit of thisdisclosure, will recognize the appropriate amount of the set retardingadditive to include for a chosen application.

Embodiments of the settable compositions further may include water. Thewater that may be used in embodiments of the settable compositionsinclude, for example, freshwater, saltwater (e.g., water containing oneor more salts dissolved therein), brine (e.g., saturated saltwaterproduced from subterranean formations), seawater, or combinationsthereof. Generally, the water may be from any source, provided that thewater does not contain an excess of compounds that may undesirablyaffect other components in the settable composition. In someembodiments, the water may be included in an amount sufficient to form apumpable slurry. In some embodiments, the water may be included in thesettable compositions of the present invention in an amount in the rangeof about 40% to about 200% by weight of cementitious components. Forexample, the water may be present in an amount ranging between any ofand/or including any of about 50%, about 75%, about 100%, about 125%,about 150%, or about 175% by weight of cementitious components. Inspecific embodiments, the water may be included in an amount in therange of about 40% to about 150% by weight of cementitious components.One of ordinary skill in the art, with the benefit of this disclosure,will recognize the appropriate amount of water to include for a chosenapplication.

Optionally, other additional additives may be added to the settablecompositions of the present invention as deemed appropriate by oneskilled in the art, with the benefit of this disclosure. Examples ofsuch additives include, but are not limited to, strength-retrogressionadditives, set accelerators, weighting agents, lightweight additives,gas-generating additives, mechanical property enhancing additives,lost-circulation materials, filtration-control additives, dispersants,fluid loss control additives, defoaming agents, foaming agents,oil-swellable particles, water-swellable particles, thixotropicadditives, and combinations thereof. Specific examples of these, andother, additives include crystalline silica, amorphous silica, fumedsilica, salts, fibers, hydratable clays, microspheres, rice husk ash,elastomers, elastomeric particles, resins, latex, combinations thereof,and the like. A person having ordinary skill in the art, with thebenefit of this disclosure, will readily be able to determine the typeand amount of additive useful for a particular application and desiredresult. Embodiments of the settable compositions may be foamed and/orextended as desired by those of ordinary skill in the art.

The settable compositions of the present invention should have a densitysuitable for a particular application as desired by those of ordinaryskill in the art, with the benefit of this disclosure. In someembodiments, the settable compositions may have a density in the rangeof from about 8 pounds per gallon (“lb/gal”) to about 16 lb/gal. Inother embodiments, the settable compositions may be foamed to a densityin the range of from about 8 lb/gal to about 13 lb/gal.

As will be appreciated by those of ordinary skill in the art,embodiments of the settable compositions may be used in a variety ofsubterranean applications, including primary and remedial cementing. Thesettable compositions of the present invention also may be used insurface applications, for example, construction cementing. Embodimentsmay include providing a settable composition and allowing the settablecomposition to set. In some embodiments, the settable composition may beallowed to set in a location that is above ground, for example, inconstruction cementing. In other embodiments, the settable compositionmay be introduced into a well bore and allowed to set. For example, thesettable composition may be placed into a space between a subterraneanformation and a conduit located in the well bore. Embodiments of thesettable compositions may comprise, for example, water and one or moreof perlite, CKD, or pumicite. Embodiments of the settable compositionsmay comprise, for example, perlite interground with hydraulic cement(e.g., Portland cement).

In primary cementing embodiments, for example, a settable compositionmay be introduced into a space between a subterranean formation and aconduit (e.g., pipe strings, liners) located in the well bore. Thesettable composition may be allowed to set to form an annular sheath ofhardened cement in the space between the subterranean formation and theconduit. Among other things, the set settable composition may form abarrier, preventing the migration of fluids in the well bore. The setsettable composition also may, for example, support the conduit in thewell bore.

In remedial cementing embodiments, a settable composition may be used,for example, in squeeze-cementing operations or in the placement ofcement plugs. By way of example, the settable composition may be placedin a well bore to plug a void or crack in the formation, in a gravelpack, in the conduit, in the cement sheath, and/or a microannulusbetween the cement sheath and the conduit.

To facilitate a better understanding of the present invention, thefollowing examples of certain aspects of some embodiments are given. Inno way should the following examples be read to limit, or define, thescope of the invention.

Example 1

A series of samples were prepared and subjected to 24-hour crushstrength tests in accordance with API Specification 10 to analyze forceresistance properties of settable compositions that comprise unexpandedperlite. The sample compositions were allowed to cure in a water bath atthe temperature indicated in the table below for twenty-four hours.Immediately after removal from the water bath, crush strengths weredetermined using a Tinius Olsen tester. The results of the crushstrength tests are set forth in the table below.

Test Nos. 1-6 were performed on samples with a 14.2 ppg and containingwater, Portland class H cement, ground unexpanded perlite, lime, andwater, as indicated in the table below. The ground unexpanded perlitewas IM-325 from Hess Pumice Products with a particle size of about 325U.S. Standard Mesh.

Test Nos. 7-8 were performed on samples with a density of 14.2 ppg andcontaining water, Portland class H cement, pumicite, and lime, asindicated in the table below. The pumicite was about 200 U.S. StandardMesh in size.

Test Nos. 9-14 were performed on samples with a density of 14.2 ppg andcontaining water, a ground cement/pumicite mixture (FineCem™ 925cement), unexpanded perlite, lime, and water, as indicated in the tablebelow. The ground cement/pumicite mixture comprised Portland Type Vcement (about 40% by weight) interground with pumicite (about 60% byweight). The ground cement/pumicite mixture had a mean particle size inthe range of about 1 to about 4 microns. The ground unexpanded perlitewas IM-325 from Hess Pumice Products with a particle size of about 325U.S. Standard Mesh.

In the following table, percent by weight is based on the weight of thePortland cement, cement/pumicite mixture, pumicite, and unexpandedperlite in the sample, and gallons per sack (gal/sk) is based on a94-pound sack of the Portland cement, cement/pumicite mixture, pumicite,and unexpanded perlite.

TABLE 1 Crush Strength Tests Ground Ground 24-Hr PortlandPumicite/Cement Unexpanded Crush Test Water Cement Mixture PumicitePerlite Lime Temp. Strength No. (gal/sk) (% by wt) (% by wt) (% by wt)(% by wt) (% by wt) (° F.) (psi) 1 7.44 100 — — — 80 330 2 7.44 100 — —— 140 674 3 6.74 75 — 25 — 80 290 4 6.74 75 — 25 — 140 777 5 6.95 75 —25 5 80 352 6 6.95 75 — 25 5 140 886 7 6.74 75 25 — — 140 835 8 6.95 7525 — 5 140 734 9 6.03 — 100 — — — 80 827 10 6.03 — 100 — — — 140 1877 115.68 — 75 — 25 — 80 597 12 5.68 — 75 — 25 — 140 2740 13 5.89 — 75 — 25 580 530 14 5.89 — 75 — 25 5 140 2610

Example 1 thus indicates that replacement of at least a portion of thePortland cement with unexpanded perlite may increase the crush strengthof the settable compositions. At 140° F., for example, the Test Nos. 2and 4 with unexpanded perlite had crush strengths of 886 psi and 777 psias compared to a crush strength of 674 psi for Test No. 1 with 100%Portland cement by weight.

Example 1 further indicates that the ground pumicite/cement mixture incombination with the unexpanded perlite may have synergistic effects onthe settable composition, in that this combination may provide increasedcrush strengths at elevated temperatures. At 140° F., for example, TestNos. 12 and 14 with the ground pumicite/cement mixture and unexpandedperlite had crush strengths of 2740 psi and 2610 psi. This crushstrength is markedly higher than the crush strengths for compositionswith 100% Portland cement (674 psi at 140° F.) and compositions withPortland cement and pumicite that were not ground to fine particle sizes(835 psi and 734 psi at 140° F.). This increased compressive strengthfor combinations of ground pumicite/cement mixture and unexpandedperlite cannot be attributed solely to the addition of expanded perliteas the combination had significantly higher crush strength than seenwith addition of unexpanded perlite to Portland cement (777 psi and 886psi at 140° F.). In addition, this increased compressive strength forcombinations of ground pumicite/cement mixture and unexpanded perlitecannot be attributed solely to the addition of expanded perlite as thecombination had significantly higher crush strength than seen with theground pumicite/cement mixture alone (1877 at 140° F.).

Example 2

An additional series of sample settable compositions were prepared andtested to analyze the force resistance properties of settablecompositions that comprise CKD and unexpanded perlite. The samplecompositions were allowed to cure in a water bath at the temperatureindicated in the table below for either 24 or 72 hours. Immediatelyafter removal from the water bath, crush strengths were determined usinga Tinius Olsen tester. The results of the crush strength tests are setforth in the table below.

Test Nos. 15-28 were performed on samples with a density of 14.2 ppg andcontaining water, CKD, ground unexpanded perlite, and lime, as indicatedin the table below. The samples further contained a cement set retarder(CFR-3™ cement set retarder, Halliburton Energy Services, Inc.) in anamount of about 0.4% by weight. The ground unexpanded perlite was IM-325from Hess Pumice Products with a particle size of about 325 U.S.Standard Mesh.

In the following table, percent by weight is based on the weight of theCKD and unexpanded perlite in the sample, and gallons per sack (gal/sk)is based on a 94-pound sack of the CKD and unexpanded perlite.

TABLE 2 Crush Strength Tests Ground CKD Unexpanded Crush Test Water (%by Perlite Lime (% Temp. Time Strength No. (gal/sk) wt) (% by wt) by wt)(° F.) (Hr) (psi) 15 5.99 100 — — 80 24 21.7 16 5.99 100 — — 140 24 26717 6.19 100 — 5 80 72 173 18 6.19 100 — 5 140 72 457 19 5.65 75 25 — 8024 23.8 20 5.65 75 25 — 140 24 969 21 5.87 75 25 5 80 24 19.6 22 5.87 7525 5 140 24 1004 23 5.5 50 50 5 80 72 124 24 5.5 50 50 5 140 72 1191 255.15 25 75 5 80 72 52 26 5.15 25 75 5 140 72 613 27 4.81 — 100 5 80 7214 28 4.81 — 100 5 140 72 145

Example 2 thus indicates that unexpanded perlite may be used to enhancethe crush strength of CKD-containing compositions. In addition, thiseffect is particularly pronounced at increased temperatures. At 140° F.,for example, Test No. 22 with 75% CKD and 25% unexpanded perlite had a72-hour crush strength of 1004 psi as compared to a 72-hour crushstrength of 457 psi for Test No. 18 with 100% CKD.

Example 3

An additional series of sample settable compositions were prepared andtested to further analyze the force resistance properties of settablecompositions that comprise CKD and unexpanded perlite. The samplecompositions were allowed to cure in a water bath at the temperatureindicated in the table below for 24 hours. Immediately after removalfrom the water bath, crush strengths were determined using a TiniusOlsen tester. The results of the crush strength tests are set forth inthe table below.

Test Nos. 29-37 were performed on samples with a density of 14.2 ppg andcontaining water, CKD, ground unexpanded perlite, and lime, as indicatedin the table below. The samples further contained a cement dispersant inan amount of about 0.4% by weight. The ground unexpanded perlite wasIM-325 from Hess Pumice Products with a particle size of about 325 U.S.Standard Mesh.

In the following table, percent by weight is based on the weight of theCKD and unexpanded perlite in the sample, and gallons per sack (gal/sk)is based on a 94-pound sack of the CKD and unexpanded perlite.

TABLE 3 Crush Strength Tests Ground 24-Hr CKD Unexpanded Crush TestWater (% by Perlite Lime (% Temp. Strength No. (gal/sk) wt) (% by wt) bywt) (° F.) (psi) 29 6.19 100 — 5 140 278 30 5.48 90 10 — 140 649 31 6.0590 10 5 140 533 32 5.7 80 20 — 140 934 33 5.92 80 20 5 140 958 34 5.4260 40 — 140 986 35 5.64 60 40 5 140 1241 36 5.28 50 50 — 140 897 37 5.550 50 5 140 1197

Example 3 thus indicates that unexpanded perlite may be used to enhancethe crush strength of CKD-containing compositions. For example, asindicated in the table above, the crush strength of the samples steadilyincreased as the concentration of unexpanded perlite in the sample wasincreased from 0% by weight to 40% by weight.

Example 4

An additional series of sample settable compositions were prepared andtested to further analyze the force resistance properties of settablecompositions that comprise CKD and unexpanded perlite. The samplecompositions were allowed to cure in a water bath at the temperatureindicated in the table below for 24 hours. Immediately after removalfrom the water bath, crush strengths were determined using a TiniusOlsen tester. The results of the crush strength tests are set forth inthe table below.

Test Nos. 38-43 were performed on samples with a density of 14.2 ppg andcontaining water, CKD, perlite, and lime, as indicated in the tablebelow. The samples further contained a cement dispersant in an amount ofabout 0.4% by weight. Test Nos. 38 and 39 contained a ground unexpandedperlite (IM-325) from Hess Pumice Products with a particle size of about325 U.S. Standard Mesh. Test Nos. 40 and 41 contained unground perliteore having a mean particle size (d50) of about 190 microns. Test Nos. 42and 43 contained expanded perlite.

In the following table, percent by weight is based on the weight of theCKD and perlite in the sample, and gallons per sack (gal/sk) is based ona 94-pound sack of the CKD and perlite.

TABLE 4 Crush Strength Tests Ground 24-Hr CKD Unexpanded PerliteExpanded Crush Test Water (% by Perlite Ore Perlite Lime Temp. StrengthNo. (gal/sk) wt) (% by wt) (% by wt) (% by wt) (% by wt) (° F.) (psi) 385.65 75 25 — — — 140 969 39 5.87 75 25 — — 5 140 1004 40 5.63 75 — 25 —— 140 199 41 5.85 75 — 25 — 5 140 204 42 1.07 75 — — 25 — 140 Notmixable 43 1.29 75 — — 25 5 140 Not mixable

Example 4 thus indicates that unexpanded perlite provides superiorstrength enhancement to CKD-containing compositions when compared tounground perlite ore and expanded perlite. Indeed, the sample with theexpanded perlite could not even be tested due to mixability problems.

Example 5

An additional series of sample settable compositions were prepared andtested to further analyze settable compositions that comprise CKD andunexpanded perlite. The sample compositions were allowed to cure in awater bath at the temperature indicated in the table below for 24 hours.Immediately after removal from the water bath, crush strengths weredetermined using a Tinius Olsen tester. The results of the crushstrength tests are set forth in the table below. The thickening time foreach sample was also determined at 140° F. in accordance with APISpecification 10.

Test Nos. 44-56 were performed on samples with a density of 12.5 ppg andcontaining CKD, perlite, and lime, as indicated in the table below. Thesamples further contained a cement dispersant in an amount of about 0.4%by weight and a cement set retarder (HR® 5 cement retarder, HalliburtonEnergy Services, Inc.). Test Nos. 45, 48, 51, and 54 contained a groundunexpanded perlite (IM-325) from Hess Pumice Products with a particlesize of about 314 U.S. Standard Mesh. Test Nos. 46, 49, 52, and 55contained unground perlite ore having a mean particle size (d50) ofabout 190. Test Nos. 47, 50, 53, and 56 contained expanded perlite.

In the following table, percent by weight is based on the weight of theCKD and perlite in the sample, and gallons per sack (gal/sk) is based ona 94-pound sack of the CKD and perlite.

TABLE 5 Crush Strength and Thickening Time Tests Ground Perlite SetThick. 24-Hr CKD Unexpanded Ore Expanded Lime Retarder Time Crush TestWater (% by Perlite (% by Perlite (% by (% by Temp. to 70 Bc StrengthNo. (gal/sk) wt) (% by wt) wt) (% by wt) wt) wt) (° F.) (psi) (psi) 4410.51 100 — — — 5 0.3 140 4:06 126 45 10.34 90 10 — — 5 0.3 140 4:17178.2 46 10.36 90 — 10 — 5 0.3 140 5:16 119 47 90 — — 10 5 0.6 140Mixable not pumpable 48 10.18 80 20 — — 5 0.3 140 4:20 311 49 10.18 80 —20 — 5 0.3 140 5:49 100 50 80 — — 20 5 0.3 140 Not mixable 51 9.84 60 40— — 5 0.3 140 5:05 508 52 60 — 40 — 5 0.15 140 9:44 88 53 60 — — 40 50.3 140 Not mixable 54 9.67 50 50 — — 5 0.3 140 8:04 616 55 50 — 50 — 50 140 23:30  78 56 50 — — 50 5 0.3 140 Not mixable

Example 5 thus indicates that unexpanded perlite provides enhancedstrength to CKD-containing compositions when compared to ungroundperlite ore and expanded perlite. In a similar manner to the precedingexample, the samples with expanded perlite could not even be tested dueto mixability problems.

Example 6

An additional series of sample settable compositions were prepared andtested to further analyze settable compositions that comprise CKD andunexpanded perlite. The sample compositions were allowed to cure in awater bath at the temperature indicated in the table below for 24 hours.Immediately after removal from the water bath, crush strengths weredetermined using a Tinius Olsen tester. The results of the crushstrength tests are set forth in the table below.

Test No. 57 was performed on a sample with a density of 12.5 ppg andcontaining water, Portland Type V cement, CKD, unground perlite ore, andpumicite, as indicated in the table below. The unground perlite ore hada mean particle size (d50) of about 190. The pumicite had a meanparticle size (d50) of about 4 microns.

Test No. 58 was performed on a sample with a density of 12.5 ppg andcontaining water, ground cement/pumicite mixture pumicite, CKD, andground unexpanded perlite. The ground cement/pumicite mixture comprisedPortland Type V cement (about 40% by weight) interground with pumicite(about 60% by weight). The ground cement/pumicite mixture had a meanparticle size of about 1-4 microns. The ground unexpanded perlite wasIM-325 from Hess Pumice Products with a particle size of about 325 U.S.Standard Mesh.

In the following table, percent by weight is based on the weight of theCKD, cement, perlite, pumicite, and/or pumicite/cement mixture in thesample, and gallons per sack (gal/sk) is based on a 94-pound sack of theCKD, cement, perlite, pumicite, and/or pumicite/cement mixture in thesample.

TABLE 6 Crush Strength Tests Ground Portland Pumicite Ground PerliteType V Cement CKD Unexpanded Ore 24-Hr Crush Water Cement PumiciteMixture (% by Perlite (% by Temp. Strength Test No. (gal/sk) (% by wt)(% by wt) (% by wt) wt) (% by wt) wt) (° F.) (psi) 57 9.52 20 30 — 25 —25 140  201 58 9.72 — — 50 25 25 — 140 1086

Example 6 thus indicates that unexpanded perlite in combination withground pumicite provides enhanced strength to CKD-containingcompositions in comparison to compositions with standard cement,pumicite, and unground perlite ore.

Example 7

An additional series of sample settable compositions were prepared andtested to analyze settable compositions that comprised intergroundperlite and hydraulic cement.

The sample settable compositions were formed by mixing the components inthe amounts set forth in the table below. The interground pumicite andcement comprised pumicite (about 60% by weight) and Portland Type Vcement (about 40% by weight) and had a mean particle size of about 1-4microns. The interground pumicite and cement are available fromHalliburton Energy Services, Inc., under the trade name FineCem™ 925cement. The interground perlite and cement comprised ground unexpandedperlite (about 60% by weight) and Portland Type V cement (about 40% byweight) and had a bimodal particle size distribution with peak particlesizes of about 4 microns and about 10 microns. The interground perliteand cement was obtained from Hess Pumice Products, Malad City, Id. Thelime was hydrated lime, obtained from Univar USA.

The sample compositions were subjected to 24-hour crush strength testsin accordance with API Specification 10. The sample compositions wereallowed to cure in a water bath at the temperature indicated in thetable below for 24 hours. Immediately after removal from the water bath,crush strengths were determined using a Tinius Olsen tester.

The results of the crush strength tests are set forth in the tablebelow.

TABLE 7 Crush Strength Tests Interground Interground Pumicite andPerlite and 24-Hr Crush Test Density Water Cement Cement Lime Temp.Strength No. (lb/gal) (% bwc¹) (% bwc) (% bwc) (% bwc) (° F.) (psi) 5914.2 52.46 100 — — 140 2870  60² 14.2 52.46 — 100 — 140 1998 61 12.592.49 100 — 5 140 1287 62 12.5 92.49 — 100 5 140 1489 63 12.5 88.9 50 50— 140 1081 64 12.5 92.49 50 50 5 140 1023 65 11 159.58 100 — — 140 31166 11 159.58 — 100 — 140 408 67 10.5 204.84 100 — — 140 105.9 68 10.5204.84 — 100 — 140 185.1 ¹The term “% bwc” refers to by weight ofcement, which in this example is either by weight of the intergroundpumicite and cement or by weight of the interground perlite and cement.²1.2 grams of CFR-3 ™ friction reducer were added to the sample settablecomposition for Test No. 60.

Example 7 thus indicates that interground perlite and hydraulic cementgenerally provides enhances compressive strength development as comparedto interground pumicite and hydraulic cement. It should be noted thatthe CFR-3™ included in Test No. 60 retarded the setting resulting in thelower 24-hour crush strength as compared to Test No. 59 with theinterground pumicite and cement.

Example 8

An additional series of sample settable compositions were prepared andtested to further analyze settable compositions that comprisedinterground perlite and hydraulic cement.

The sample settable compositions were formed by mixing the components inthe amounts set forth in the table below. The interground pumicite andcement comprised pumicite (about 60% by weight) and Portland Type Vcement (about 40% by weight) and had a mean particle size of about 1-4microns. The interground pumicite and cement are available fromHalliburton Energy Services, Inc., under the trade name FineCem™ 925cement. The interground perlite and cement comprised ground unexpandedperlite (about 60% by weight) and Portland Type V cement (about 40% byweight) and had a bimodal particle size distribution with peak particlesizes of about 4 microns and about 10 microns. The interground perliteand cement was obtained from Hess Pumice Products, Malad City, Id.

The sample compositions were subjected to 24-hour crush strength testsin accordance with API Specification 10. The sample compositions wereallowed to cure in a water bath at the temperature indicated in thetable below for 24 hours. Immediately after removal from the water bath,crush strengths were determined using a Tinius Olsen tester. Thethickening time for each sample was also determined at 140° F. inaccordance with API Specification 10.

The results of the crush strength and thickening time tests are setforth in the table below.

TABLE 8 Crush Strength and Thickening Time Tests Thick. IntergroundInterground Time 24-Hr Pumicite Perlite and to 70 Crush Test DensityWater and Cement Cement Retarder Temp. Bc² Strength No. (lb/gal) (%bwc¹) (% bwc) (% bwc) (% bwc) (° F.) (hr:min) (psi) 69 12.5 88.85 100 — 0.4 HR ®-5 140 8:56 — 70 12.5 88.87 100 — 0.25 HR ®-5 140 4:57 — 7112.5 88.87 — 100 0.25 HR ®-5 140 3:54 — 72 12.5 89.0 100 — 0.25 HR ®-800140 2:57 — 73 12.5 89.05 100 — 0.25 HR ®-800 140 4:11  919 74 12.5 89.05— 100 0.25 HR ®-800 140 4:15 1178 ¹The abbreviation “% bwc” refers to byweight of cement, which in this example is either by weight of theinterground pumicite and cement or by weight of the interground perliteand cement. ²The abbreviation “Bc” refers to Bearden units ofconsistency.

Example 8 thus indicates that settable compositions comprisinginterground perlite and hydraulic cement may have acceptable thickeningtimes for use in subterranean applications. Example 8 further indicatesthat interground perlite and hydraulic cement generally providesenhanced compressive strength development and can be similarlycontrolled with retarders as compared to interground pumicite andhydraulic cement.

Example 9

An additional series of sample settable compositions were prepared andtested to further analyze settable compositions that comprisedinterground perlite and hydraulic cement.

The sample settable compositions were formed by mixing the components inthe amounts set forth in the table below. The interground pumicite andcement comprised pumicite (about 60% by weight) and Portland Type Vcement (about 40% by weight) and had a mean particle size of about 1-4microns. The interground pumicite and cement are available fromHalliburton Energy Services, Inc., under the trade name FineCem™ 925cement. The interground perlite and cement comprised ground unexpandedperlite (about 60% by weight) and Portland Type V cement (about 40% byweight) and had a bimodal particle size distribution with peak particlesizes of about 4 microns and about 10 microns. The interground perliteand cement was obtained from Hess Pumice Products, Malad City, Id.

Free water data was then gathered for each sample composition inaccordance with API Specification 10. The free water data is set forthin the table below.

TABLE 9 Free Water Data Interground Interground Pumicite and Perlite andFree Test Density Water Cement Cement Temp. Water No. (lb/gal) (% bwc¹)(% bwc) (% bwc) (° F.) (cc²) 75 11 159.58 100 — 80 2 76 11 159.58 — 10080 0 77 10.5 204.84 100 — 80 8 78 10.5 204.84 — 100 80 1 79 10.5 204.84 50  50 80 2 80 10 277.18 100 — 80 56 81 10 277.18 — 100 80 14 ¹Theabbreviation “% bwc” refers to by weight of cement, which in thisexample is either by weight of the interground pumicite and cement or byweight of the interground perlite and cement. ²The abbreviation “cc”refers to cubic centimeters.

Example 9 thus indicates that settable compositions comprisinginterground perlite and hydraulic cement may have provide lower levelsof free water as compared to interground pumicite and hydraulic cement.

It should be understood that the compositions and methods are describedin terms of “comprising,” “containing,” or “including” variouscomponents or steps, the compositions and methods can also “consistessentially of” or “consist of” the various components and steps.

For the sake of brevity, only certain ranges are explicitly disclosedherein. However, ranges from any lower limit may be combined with anyupper limit to recite a range not explicitly recited, as well as, rangesfrom any lower limit may be combined with any other lower limit torecite a range not explicitly recited, in the same way, ranges from anyupper limit may be combined with any other upper limit to recite a rangenot explicitly recited. Additionally, whenever a numerical range with alower limit and an upper limit is disclosed, any number and any includedrange falling within the range is specifically disclosed. In particular,every range of values (of the form, “from about a to about b,” or,equivalently, “from approximately a to b,” or, equivalently, “fromapproximately a-b”) disclosed herein is to be understood to set forthevery number and range encompassed within the broader range of valueseven if not explicitly recite. Thus, every point or individual value mayserve as its own lower or upper limit combined with any other point orindividual value or any other lower or upper limit, to recite a rangenot explicitly recited.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Although individual embodiments arediscussed, the invention covers all combinations of all thoseembodiments. Furthermore, no limitations are intended to the details ofconstruction or design herein shown, other than as described in theclaims below. Also, the terms in the claims have their plain, ordinarymeaning unless otherwise explicitly and clearly defined by the patentee.It is therefore evident that the particular illustrative embodimentsdisclosed above may be altered or modified and all such variations areconsidered within the scope and spirit of the present invention.

1. A method of cementing comprising: providing a settable compositioncomprising perlite, hydraulic cement, and water, wherein the perlite andhydraulic cement are interground prior to combination with the water toform the settable composition; and allowing the settable composition toset.
 2. The method of claim 1 wherein the perlite comprises unexpandedperlite.
 3. The method of claim 1 wherein the perlite and the hydrauliccement were interground to a mean particle about 0.1 microns to about400 microns.
 4. The method of claim 1 wherein the perlite and thehydraulic cement were interground to a mean particle about 0.5 micronsto about 10 microns.
 5. The method of claim 1 wherein the perlite ispresent in an amount of about 40% to about 80% by weight of the perliteand hydraulic cement, and wherein the hydraulic cement is present in anamount of about 20% to about 60% by weight of the perlite and hydrauliccement.
 6. The method of claim 1 wherein the hydraulic cement comprisesat least one cement selected from the group consisting of a Portlandcement, a pozzolana cement, a gypsum cement, a high-alumina-contentcement, a slag cement, a silica/lime cement, and any combinationthereof.
 7. The method of claim 1 wherein the hydraulic cement comprisesa Portland cement.
 8. The method of claim 1 wherein the perlite and thehydraulic cement were interground with at least one additional componentselected from the group consisting of cement kiln dust and pumicite. 9.The method of claim 1 wherein the settable composition further comprisescement kiln dust.
 10. The method of claim 1 wherein the settablecomposition further comprises pumicite.
 11. The method of claim 1wherein the settable composition further comprises at least one additiveselected from the group consisting of lime, fly ash, slag cement,metakaolin, shale, zeolite, crystalline silica, amorphous silica, fumedsilica, salt, fiber, hydratable clay, microsphere, rice husk ash,elastomer, elastomeric particle, resin, latex, and any combinationthereof.
 12. The method of claim 1 wherein the settable compositionfurther comprises at least one additive selected from the groupconsisting of a set retarding additive, a strength-retrogressionadditive, a set accelerator, a weighting agent, a lightweight additive,a gas-generating additive, a mechanical property enhancing additive, alost-circulation material, a filtration-control additive, a dispersant,a fluid loss control additive, a defoaming agent, a foaming agent, anoil-swellable particle, a water-swellable particle, a thixotropicadditive, and any combination thereof.
 13. The method of claim 1 furthercomprising introducing the settable composition into a well bore. 14.The method of claim 13 wherein the settable composition is allowed toset in the well bore in an annulus between a subterranean formation anda conduit in the well bore.
 15. The method of claim 13 furthercomprising squeezing the settable composition in an opening, the openingcomprising at least one opening selected from the group consisting of anopening in a subterranean formation, an opening in a gravel pack, anopening in a conduit, and a microannulus between a cement sheath and aconduit.
 16. A method of cementing comprising: providing a settablecomposition comprising unexpanded perlite, hydraulic cement, and water,wherein the unexpanded perlite and hydraulic cement are intergroundprior to combination with the water to form the settable composition;introducing the settable composition into a well bore; and allowing thesettable composition to set.
 17. The method of claim 16 wherein theperlite and hydraulic cement were interground to a mean particle about0.5 microns to about 10 microns.
 18. The method of claim 16 wherein theperlite is present in an amount of about 40% to about 80% by weight ofthe perlite and hydraulic cement, and wherein the hydraulic cement in anamount of about 20% to about 60% by weight of the perlite and hydrauliccement.
 19. The method of claim 16 wherein the hydraulic cementcomprises at least one cement selected from the group consisting of aPortland cement, a pozzolana cement, a gypsum cement, ahigh-alumina-content cement, a slag cement, a silica/lime cement, andany combination thereof.
 20. The method of claim 16 wherein thehydraulic cement comprises a Portland cement.
 21. The method of claim 16wherein the perlite and the hydraulic cement were interground with atleast one additional component selected from the group consisting ofcement kiln dust and pumicite.
 22. The method of claim 16 wherein thesettable composition further comprises cement kiln dust.
 23. The methodof claim 16 wherein the settable composition further comprises pumicite.24. The method of claim 16 wherein the settable composition furthercomprises at least one additive selected from the group consisting oflime, fly ash, slag cement, metakaolin, shale, zeolite, crystallinesilica, amorphous silica, fumed silica, salt, fiber, hydratable clay,microsphere, rice husk ash, elastomer, elastomeric particle, resin,latex, and any combination thereof.
 25. The method of claim 16 whereinthe settable composition further comprises at least one additiveselected from the group consisting of a set retarding additive, astrength-retrogression additive, a set accelerator, a weighting agent, alightweight additive, a gas-generating additive, a mechanical propertyenhancing additive, a lost-circulation material, a filtration-controladditive, a dispersant, a fluid loss control additive, a defoamingagent, a foaming agent, an oil-swellable particle, a water-swellableparticle, a thixotropic additive, and any combination thereof.
 26. Themethod of claim 16 wherein the settable composition is allowed to set inthe well bore in an annulus between a subterranean formation and aconduit in the well bore.
 27. The method of claim 16 further comprisingsqueezing the settable composition in an opening, the opening comprisingat least one opening selected from the group consisting of an opening ina subterranean formation, an opening in a gravel pack, an opening in aconduit, and a microannulus between a cement sheath and a conduit.
 28. Acomposition comprising: interground perlite and hydraulic cement.